U.S. patent application number 12/730538 was filed with the patent office on 2010-09-30 for method of producing gas barrier layer.
This patent application is currently assigned to FUJIFILM CORPORATION. Invention is credited to Toshiya TAKAHASHI.
Application Number | 20100247806 12/730538 |
Document ID | / |
Family ID | 42784582 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100247806 |
Kind Code |
A1 |
TAKAHASHI; Toshiya |
September 30, 2010 |
METHOD OF PRODUCING GAS BARRIER LAYER
Abstract
The producing method of a gas barrier layer uses a material
having at least one Si--H bond, a material having at least one N-H
bond, and at least one of nitrogen gas, hydrogen gas and a noble
gas and forms the gas barrier layer by plasma-enhanced CVD using a
plasma in which an emission intensity A of emission at 414 nm, an
emission intensity B of emission at 336 nm, an emission intensity C
of emission at 337 nm, and an emission intensity D of emission at
656 nm satisfy formulas a to c: 2<B/A<20 Formula a C/B<2
Formula b 0.5<D/B<50. Formula c
Inventors: |
TAKAHASHI; Toshiya;
(Kanagawa, JP) |
Correspondence
Address: |
YOUNG & THOMPSON
209 Madison Street, Suite 500
Alexandria
VA
22314
US
|
Assignee: |
FUJIFILM CORPORATION
Minami-ashigara,shi
JP
|
Family ID: |
42784582 |
Appl. No.: |
12/730538 |
Filed: |
March 24, 2010 |
Current U.S.
Class: |
427/578 |
Current CPC
Class: |
C23C 16/505 20130101;
C23C 16/545 20130101; C23C 16/345 20130101 |
Class at
Publication: |
427/578 |
International
Class: |
C23C 16/513 20060101
C23C016/513; C23C 16/42 20060101 C23C016/42 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 25, 2009 |
JP |
2009-074172 |
Claims
1. A method of producing a gas barrier layer comprising: using a
material having at least one Si--H bond, a material having at least
one N--H bond, and at least one of nitrogen gas, hydrogen gas and a
noble gas; and forming said gas barrier layer by plasma-enhanced
CVD using a plasma in which an emission intensity A of emission at
414 nm, an emission intensity B of emission at 336 nm, an emission
intensity C of emission at 337 nm, and an emission intensity D of
emission at 656 nm satisfy formulas a to c: 2<B/A<20 Formula
a C/B<2 Formula b 0.5<D/B<50. Formula c
2. The method according to claim 1, wherein said emission
intensities A to D are measured and at least one of plasma
excitation power, pressure control means and each amount of
supplied materials is feedback-controlled based on measurement
results so that the formulas a to c are satisfied.
3. The method according to claim 1, wherein said gas barrier layer
is formed on an elongated substrate traveling in a longitudinal
direction.
4. The method according to claim 3, wherein a region where said gas
barrier layer was formed in a state in which at least one of the
formulas a to c was not satisfied for at least 1 consecutive second
is detected.
5. The method according to claim 4, wherein said region is marked
where said gas barrier layer was formed in the state in which at
least one of the formulas a to c was not satisfied for at least 1
consecutive second.
6. The method according to claim 5, wherein marking is made to put
visible marks on said region.
7. The method according to claim 5, wherein marking is made outside
a region for use as a product.
8. The method according to claim 1, wherein said gas barrier layer
is formed on a substrate made of an organic material or a substrate
having an organic base material.
9. The method according to claim 1, wherein said gas barrier layer
is formed with a substrate temperature kept at 120.degree. C. or
less.
10. The method according to claim 1, wherein said gas barrier layer
is formed on a substrate and at least a part of a surface of said
substrate is formed with an organic material.
11. The method according to claim 1, wherein another gas barrier
layer is deposited on a substrate having the gas barrier layer
formed by the method according to claim 1.
12. The method according to claim 1, wherein said gas barrier layer
is formed as AC or DC bias power is applied to a substrate, said
emission intensities A to D are measured and the bias power applied
to a substrate is feedback-controlled based on measurement results
so that the formulas a to c are satisfied.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a method of producing a gas
barrier layer by using plasma-enhanced CVD. More specifically, the
invention relates to a gas barrier layer production method capable
of depositing a gas barrier layer having not only excellent gas
barrier properties but also excellent oxidation resistance and high
transparency.
[0002] A gas barrier layer (a water-vapor barrier layer) is formed
not only on sites or parts requiring moisture resistance in various
devices including optical devices, display devices (e.g.
liquid-crystal displays and organic EL displays), semiconductor
devices and thin-film solar batteries, but also in packaging
materials used to package food, clothing, electronic components,
etc.
[0003] Layers made of various materials such as silicon oxide,
silicon oxynitride and aluminum oxide are known gas barrier layers.
A gas barrier layer made of silicon nitride is known as one of
those layers. Plasma-enhanced CVD is a known method of producing a
gas barrier layer made of silicon nitride.
[0004] For example, US 2008/0211066 A1 describes a gas barrier
layer production method in which a gas barrier layer made of
silicon nitride is formed on a substrate surface by plasma-enhanced
CVD using silane gas, ammonia gas and a carrier gas, wherein two or
more silicon nitride sublayers having different Si/N composition
ratios are deposited by maintaining the substrate temperature at
200.degree. C. or less and adjusting the flow rate ratio of the
ammonia gas to the silane gas.
[0005] The production method described in US 2008/0211066 A1 is
capable of obtaining a gas barrier layer which exhibits high
oxidation resistance in a high temperature and high humidity
environment, has few pinholes and exhibits high transparency
(optical transmittance).
SUMMARY OF THE INVENTION
[0006] An oxidized gas barrier layer reduces the gas barrier
properties, whereby desired gas barrier properties cannot be
exhibited. Optical applications including displays and lenses
require high transparency in order to prevent the device
performance from deteriorating.
[0007] To this end, as also described in US 2008/0211066 A1, the
gas barrier layer is required to have excellent gas barrier
properties, transparency and oxidation resistance depending on the
intended use, and a variety of gas barrier layers and gas barrier
layer production methods have been proposed. However, increasingly
strict requirements are recently imposed on those properties of the
gas barrier layer, and some of commonly used gas barrier layers do
not satisfy the required performance. For example, the gas barrier
layer of a two-sublayer structure described in US 2008/0211066 A1
which includes a sublayer containing a large amount of silicon and
exhibiting excellent oxidation resistance can achieve excellent
oxidation resistance but may often not achieve high performance in
terms of transparency because of the presence of the sublayer
containing a large amount of silicon.
[0008] Accordingly, a production method has been desired with which
a gas barrier layer having more excellent gas barrier properties,
transparency and oxidation resistance can be consistently
produced.
[0009] In order to solve the aforementioned prior art problems, an
object of the present invention is to provide a gas barrier layer
production method capable of consistently depositing a gas barrier
layer which can exhibit excellent gas barrier properties even in a
monolayer structure and also exhibits excellent transparency and
oxidation resistance.
[0010] In order to achieve the above object, the present invention
provides a method of producing a gas barrier layer comprising:
using a material having at least one Si--H bond, a material having
at least one N--H bond, and at least one of nitrogen gas, hydrogen
gas and a noble gas; and forming the gas barrier layer by
plasma-enhanced CVD using a plasma in which an emission intensity A
of emission at 414 nm, an emission intensity B of emission at 336
nm, an emission intensity C of emission at 337 nm, and an emission
intensity D of emission at 656 nm satisfy formulas a to c:
2<B/A<20 Formula a
C/B<2 Formula b
0.5<D/B<50. Formula c
[0011] Preferably, the emission intensities A to D are measured and
at least one of plasma excitation power, pressure control means and
each amount of supplied materials is feedback-controlled based on
measurement results so that the formulas a to c are satisfied.
[0012] The gas barrier layer is preferably formed on an elongated
substrate traveling in a longitudinal direction.
[0013] A region where the gas barrier layer was formed in a state
in which at least one of the formulas a to c was not satisfied for
at least 1 consecutive second is preferably detected.
[0014] The region is preferably marked where the gas barrier layer
was formed in the state in which at least one of the formulas a to
c was not satisfied for at least 1 consecutive second.
[0015] Marking is preferably made to put visible marks on the
region.
[0016] Marking is preferably made outside a region for use as a
product.
[0017] The gas barrier layer is preferably formed on a substrate
made of an organic material or a substrate having an organic base
material.
[0018] The gas barrier layer is preferably formed with a substrate
temperature kept at 120.degree. C. or less.
[0019] Preferably, the gas barrier layer is formed on a substrate
and at least a part of a surface of the substrate is formed with an
organic material.
[0020] Another gas barrier layer is preferably deposited on a
substrate having the gas barrier layer formed by this method.
[0021] Preferably, the gas barrier layer is formed as AC or DC bias
power is applied to a substrate, the emission intensities A to D
are measured and the bias power applied to a substrate is
feedback-controlled based on measurement results so that the
formulas a to c are satisfied.
[0022] The present invention is capable of consistently producing a
gas barrier layer which exhibits excellent gas barrier properties
even in a monolayer structure and is excellent not only in the gas
barrier properties but also oxidation resistance in a high
temperature and high humidity environment and transparency in a
visible light region by using a material having at least one Si--H
bond, a material having at least one N-H bond, and at least one of
nitrogen, hydrogen and a noble gas, and by forming the gas barrier
layer with the plasma state controlled in accordance with emission
at specified wavelengths due to generated radicals. The gas barrier
layer has excellent gas barrier properties even in the monolayer
structure and the present invention can therefore minimize the
reduction of the transparency due to the multilayer structure of
the gas barrier layer while improving the productivity.
[0023] Therefore, the present invention is advantageously used in
various applications requiring the gas barrier layer which has not
only high gas barrier properties but also high transparency and
oxidation resistance, as exemplified by the production of various
displays and lighting devices using organic ELs and liquid crystals
and the production of solar batteries.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a schematic view showing an embodiment of the
production device for implementing the gas barrier layer production
method of the present invention.
[0025] FIG. 2 is a schematic view showing an exemplary substrate
for use in the production method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Next, the method for producing a gas barrier layer according
to the present invention is described in detail by referring to the
preferred embodiment shown in the accompanying drawings.
[0027] FIG. 1 is a schematic view showing an embodiment of the
production device for implementing the gas barrier layer production
method of the present invention.
[0028] The illustrated gas barrier layer production device 10
produces a gas barrier film by depositing or forming a gas barrier
layer by plasma-enhanced CVD on a surface of an elongated substrate
Z, that is, a film material as it travels in a longitudinal
direction.
[0029] This production device 10 is a film deposition device by a
so-called roll-to-roll system with which the substrate Z is fed
from a substrate roll 20 having the elongated substrate Z wound
into a roll, a gas barrier layer is formed on the substrate Z
traveling in the longitudinal direction and the substrate Z having
the gas barrier layer formed thereon, that is, the gas barrier film
is wound into a roll.
[0030] In the production method of the present invention, an
example of the substrate (substrate for film deposition) that may
be preferably used includes an elongated sheet as in the
illustrated case, but various articles (members/base materials)
including a film cut into a sheet with a predetermined length
(i.e., cut sheet), optical devices such as lenses and optical
filters, photoelectric transducers such as organic EL devices and
solar batteries, and display panels such as liquid-crystal displays
and electronic paper may also be advantageously used for the
substrate.
[0031] The material of the substrate is also not particularly
limited and various materials may be used as long as a gas barrier
layer can be formed by plasma-enhanced CVD. The substrate may be
made of organic materials such as plastic films (resin films) or of
inorganic materials such as metals and ceramics.
[0032] As described later in detail, the gas barrier layer
deposited by the production method of the present invention has
highly excellent oxidation resistance and has therefore poor
chemical/physical compatibility with silicon nitride compared to a
silicon wafer substrate and a metallic substrate, and can be
advantageously used particularly in applications in which a
material such as a plastic film having difficulty in achieving high
barrier properties and high oxidation resistance is used for the
substrate (base material). Specific examples of the substrate that
may be advantageously used include substrates made of organic
materials such as polyethylene terephthalate (PET), polyethylene
naphthalate, polyethylene, polypropylene, polystyrene, polyamide,
polyvinyl chloride, polycarbonate, polyacrylonitrile, polyimide,
polyacrylate, and polymethacrylate.
[0033] In the present invention, base materials such as plastic
films and lenses having layers (films) formed thereon to impart
various functions may be used for the substrate. Exemplary layers
include a protective layer, an adhesive layer, a light-reflecting
layer, a light-shielding layer, a planarizing layer, a buffer
layer, and a stress-relief layer.
[0034] The substrate used may be one having one layer formed on a
base material or one having a plurality of layers such as layers a
to f formed on a base material B as conceptually shown in FIG. 2.
In a substrate having one or more than one layer formed on the base
material B, at least one of the layers (at least one of the layers
a to f in FIG. 2) may be a gas barrier layer formed by the
production method of the present invention. A substrate having the
gas barrier layers of the present invention and other layers formed
alternately may also be advantageously used, and in this case, the
layers other than the gas barrier layers may be made of a single
material or different materials.
[0035] At least one of the layers (at least one of the layers a to
f in FIG. 2) may also be patterned.
[0036] In cases where irregularities or foreign substances having
considerably larger sizes than the thickness of the gas barrier
layer are formed at the surface of the substrate, the gas barrier
properties deteriorate, making it impossible to obtain desired gas
barrier properties even if high oxidation resistance is
achieved.
[0037] Therefore, the substrate used is preferably one which has a
sufficiently smooth surface and to which few foreign substances
adhere.
[0038] As described above, the production device 10 shown in FIG. 1
is a film deposition device by a so-called roll-to-roll system in
which the substrate Z is fed from the substrate roll 20 having the
elongated substrate Z wound into a roll, a gas barrier layer is
formed on the substrate Z traveling in the longitudinal direction
and the substrate Z having the gas barrier layer formed thereon is
rewound into a roll. The production device 10 includes a feed
chamber 12, a film deposition chamber 14 and a take-up chamber
16.
[0039] In addition to the illustrated members, the production
device 10 may also have various members of a plasma CVD device by
means of a roll-to-roll system including various sensors, and
various members (transport means) for transporting the substrate Z
along a predetermined path, as exemplified by a transport roller
pair and a guide member for regulating the position in the width
direction of the substrate Z. In addition, the production device 10
may include a plurality of plasma CVD film deposition chambers.
Alternatively, at least one film deposition chamber for depositing
a film by other vapor deposition techniques than plasma-enhanced
CVD, flash evaporation or sputtering and/or at least one surface
treatment chamber for plasma treatment may be connected to the
production device.
[0040] The feed chamber 12 includes a rotary shaft 24, a guide
roller 26 and a vacuum evacuation means 28.
[0041] The substrate roll 20 into which the elongated substrate Z
is wound is mounted on the rotary shaft 24 of the feed chamber
12.
[0042] Upon mounting of the substrate roll 20 on the rotary shaft
24, the substrate Z travels along a predetermined travel path
starting from the feed chamber 12 and passing through the film
deposition chamber 14 to reach a take-up shaft 30 of the take-up
chamber 16.
[0043] Feeding of the substrate Z from the substrate roll 20 and
winding of the substrate Z on the take-up shaft 30 of the take-up
chamber 16 are carried out in synchronism in the production device
10 to continuously form the gas barrier layer on the elongated
substrate Z in the film deposition chamber 14 by plasma-enhanced
CVD as the substrate Z travels in its longitudinal direction along
the predetermined travel path.
[0044] In the feed chamber 12, the rotary shaft 24 is rotated by a
drive source (not shown) in a clockwise direction in FIG. 1 so that
the substrate Z is fed from the substrate roll 20, is guided by the
guide roller 26 along the predetermined path and passes through a
slit 32a provided in a partition wall 32 to reach the film
deposition chamber 14.
[0045] In the preferred embodiment of the illustrated production
device 10, the feed chamber 12 and the take-up chamber 16 are
provided with vacuum evacuation means 28 and 60, respectively. The
pressures in the neighboring chambers are prevented from affecting
the degree of vacuum in the film deposition chamber 14 (formation
of the gas barrier layer) by providing the vacuum evacuation means
in these chambers so that the chambers may have during film
deposition the same degree of vacuum (pressure) as the film
deposition chamber 14 to be described later.
[0046] The vacuum evacuation means 28 is not particularly limited,
and exemplary means that may be used include vacuum pumps such as a
turbo pump, a mechanical booster pump, a dry pump, and a rotary
pump, an assist means such as a cryogenic coil, and various other
known (vacuum) evacuation means which use a means for adjusting the
ultimate degree of vacuum or the amount of air discharged and are
employed in vacuum deposition devices. In this regard, the same
holds true for other vacuum evacuation means 50 and 60.
[0047] The present invention is not limited to the embodiment in
which all the chambers are provided with vacuum evacuation means,
and the feed chamber 12 and the take-up chamber 16 which require no
vacuum evacuation treatment may not be provided with vacuum
evacuation means. However, in order to minimize the adverse effect
of the pressures in these chambers on the degree of vacuum in the
film deposition chamber 14, the size of the portion such as the
slit 32a through which the substrate Z passes may be made as small
as possible, or a subchamber may be provided between the adjacent
chambers so that the internal pressure of the subchamber is
reduced.
[0048] Even in the illustrated production device 10 in which all
the chambers have the vacuum evacuation means, it is preferred to
minimize the size of the portion such as the slit 32a through which
the substrate Z passes.
[0049] As described above, the substrate Z is guided by the guide
roller 26 to reach the film deposition chamber 14.
[0050] The film deposition chamber 14 is used to deposit or form a
gas barrier layer on a surface of the substrate Z by capacitively
coupled plasma-enhanced CVD (hereinafter abbreviated as
CCP-CVD).
[0051] The plasma-enhanced CVD used in the present invention is not
limited to CCP-CVD as in the illustrated case, and various types of
plasma-enhanced CVD including inductively coupled plasma-enhanced
CVD (ICP-CVD), microwave plasma CVD, electron cyclotron resonance
CVD (ECR-CVD) and atmospheric pressure barrier discharge CVD are
all available. The same principle can be applied to obtain the same
effect even in catalytic CVD (Cat-CVD) if there is emission at the
wavelengths according to the present invention.
[0052] In the illustrated embodiment, the film deposition chamber
14 includes a drum 36, a shower head electrode 38, guide rollers 40
and 42, a gas supply means 46, an RF power source 48, the vacuum
evacuation means 50, a plasma emission measurement means 52, a
marking means 54, and a control means 56.
[0053] The drum 36 in the film deposition chamber 14 is a
cylindrical member rotating about the central axis in the
counterclockwise direction in FIG. 1, and the substrate Z guided by
the guide roller 40 along the predetermined path is wrapped over a
predetermined region of the peripheral surface to travel in the
longitudinal direction as the substrate Z is held at a
predetermined position facing the shower head electrode 38 to be
described later.
[0054] The drum 36 also serves as a counter electrode in CCP-CVD
and forms an electrode pair with the shower head electrode 38.
[0055] To this end, the drum 36 is connected to a bias power source
or grounded (connection is not shown in both the cases).
Alternatively, the drum 36 may be capable of switching between
connection to the bias power source and grounding.
[0056] In the production method of the present invention, the gas
barrier layer is preferably formed by adjusting the temperature of
the substrate to 120.degree. C. or less. It is particularly
preferred to form the gas barrier layer by adjusting the
temperature of the substrate to 80.degree. C. or less.
[0057] By adjusting the temperature of the substrate to 120.degree.
C. or less, preferred results are obtained in that a gas barrier
layer having advantageously high gas barrier properties and
oxidation resistance and a low-stress gas barrier layer can be
formed on a less heat-resistant plastic film substrate such as a
PEN substrate or on a substrate using a less heat-resistant organic
material as the base material. In addition, by adjusting the
temperature of the substrate to 80.degree. C. or less, preferred
results are obtained in that a gas barrier layer having
advantageously high gas barrier properties and oxidation resistance
and a low-stress gas barrier layer can be formed on a less
heat-resistant plastic film substrate such as a PET substrate.
[0058] In order to form the gas barrier layer at 120.degree. C. or
less in the illustrated production device 10, the drum 36
preferably serves as the temperature adjusting means for keeping
the substrate Z at a temperature of 120.degree. C. or less, in
other words, the temperature adjusting means is preferably built
into the drum 36.
[0059] The temperature adjusting means of the drum 36 is not
particularly limited and various types of temperature adjusting
means including one in which a refrigerant is circulated and a
cooling means using a piezoelectric element are all available.
[0060] The shower head electrode 38 is of a known type used in film
deposition by means of CCP-CVD.
[0061] In the illustrated embodiment, the shower head electrode 38
is, for example, in the form of a hollow rectangular solid and is
disposed so that its largest surface faces the peripheral surface
of the drum 36 and the perpendicular from the center of the largest
surface coincides with the normal of the drum 36 with respect to
its peripheral surface. A large number of through holes are formed
at the whole surface of the shower head electrode 38 facing the
drum 36.
[0062] In the illustrated production device 10, one shower head
electrode (film deposition means by CCP-CVD) is provided in the
film deposition chamber 14. However, this is not the sole case of
the present invention and a plurality of shower head electrodes may
be disposed in the direction of travel of the substrate Z. In this
regard, the same holds true when using plasma-enhanced CVD of other
type than CCP-CVD. For example, when a gas barrier layer is formed
or produced by ICP-CVD, a plurality of (induction) coils for
forming an induced electric field (induced magnetic field) may be
provided along the direction of travel of the substrate Z.
[0063] The present invention is not limited to the case in which
the gas barrier layer is formed by using the shower head electrode,
and the gas barrier layer may be formed by using a common electrode
in plate form and a gas supply nozzle.
[0064] The gas supply means 46 is of a known type used in vacuum
deposition devices such as plasma CVD devices, and supplies a
material into the shower head electrode 38.
[0065] As described above, a large number of through holes are
formed at the surface of the shower head electrode 38 facing the
drum 36. Therefore, the material supplied into the shower head
electrode 38 passes through the through holes to be introduced into
the space between the shower head electrode 38 and the drum 36.
[0066] The production device 10 for implementing the production
method of the present invention uses a material having at least one
Si--H bond, a material having at least one N--H bond, and at least
one of nitrogen gas, hydrogen gas and a noble gas. In other words,
the present invention forms a silicon nitride film for the gas
barrier layer.
[0067] The gas barrier layer produced by the production method of
the present invention may of course include not only silicon
nitride but also hydrogen or other various substances inevitably
incorporated therein. The gas barrier layer produced by the
production method of the present invention may be of a crystalline
or amorphous structure, or of a combination of both the
structures.
[0068] Compounds having at least one Si--H bond can all be used for
the material having at least one Si--H bond.
[0069] Specific examples thereof include silane, disilane and
trimethylsilane (TMS). Of these, silane and disilane are
preferred.
[0070] A plurality of materials having at least one Si--H bond may
be used in combination.
[0071] Compounds having at least one N--H bond can all be used for
the material having at least one N--H bond.
[0072] Exemplary materials include ammonia and hydrazine. Of these,
ammonia is preferred.
[0073] A plurality of materials having at least one N--H bond may
be used in combination.
[0074] In addition to these materials, the present invention
further uses at least one of nitrogen gas, hydrogen gas and a noble
gas.
[0075] These material gases may be used alone or in combination but
nitrogen gas combined with hydrogen gas, nitrogen gas combined with
helium gas, and nitrogen gas combined with argon gas are
preferred.
[0076] The production method of the present invention is not
limited to the embodiment in which gases (gaseous material) are
used for the material of the gas barrier layer and a liquid
material may be used and vaporized to form the gas barrier layer.
Alternatively, the gaseous material and the liquid material may be
used in combination to form the gas barrier layer.
[0077] The RF power source 48 is one for supplying plasma
excitation power to the shower head electrode 38. Known RF power
sources used in various plasma CVD devices can be all used for the
RF power source 48.
[0078] In addition, the vacuum evacuation means 50 evacuates the
film deposition chamber 14 to keep it at a predetermined film
deposition pressure in order to form the gas barrier layer by
plasma-enhanced CVD, and is of a known type used in vacuum
deposition devices as described above.
[0079] The control means 56 controls the operations of the gas
supply means 46, the RF power source 48 and the vacuum evacuation
means 50. The control means 56 will be described later in
detail.
[0080] The plasma emission measurement means 52 is a portion where
the emission intensity of emission at 414 nm (emission intensity
A), the emission intensity of emission at 336 nm (emission
intensity B), the emission intensity of emission at 337 nm
(emission intensity C) and the emission intensity of emission at
656 nm (emission intensity D) are measured during the deposition of
the gas barrier layer by plasma-enhanced CVD and supplied to the
control means 56.
[0081] The position at which the plasma emission measurement means
52 measures the emission intensities at the respective wavelengths
is not limited as long as the plasma emission can be detected at
that position. However, in order to obtain the benefits of the
present invention more effectively, the emission intensities are
preferably measured at such a distance from the plasma that no
disturbance is given to the plasma and a satisfactory S/N ratio is
obtained, and the position at which the emission in the uniform
discharge region near the center of the discharge volume can be
detected is preferred.
[0082] It is preferred to obtain each of the emission intensities
according to the present invention by subtracting the background
(signal intensity when the plasma is off) from the signal intensity
at which the plasma emission was measured.
[0083] As described above, the production method of the present
invention uses the material having at least one Si--H bond, the
material having at least one N--H bond and at least one of nitrogen
gas, hydrogen gas and a noble gas to form the gas barrier layer by
plasma-enhanced CVD.
[0084] In the gas barrier layer (silicon nitride film) deposition
system using such materials, the emission at 414 nm (emission
intensity A) is mainly derived from SiH radicals, the emission at
336 nm (emission intensity B) is mainly derived from NH radicals,
the emission at 337 nm (emission intensity C) is mainly derived
from N.sub.2 radicals, and the emission at 656 nm (emission
intensity D) is mainly derived from H radicals.
[0085] By depositing the gas barrier layer using the plasma in
which the 4 emission intensities A to D satisfy formulas a to c to
be described later, the production method of the present invention
is capable of consistently producing the gas barrier layer which is
excellent not only in the gas barrier properties but also in the
oxidation resistance in a high temperature and high humidity
environment and the transparency.
[0086] In the production method of the present invention, the
plasma emission measurement means 52 is not particularly limited,
and various types of spectrometers and spectrophotometers with
which the emission intensity can be measured by dividing light into
the four wavelength components can all be used, and commercially
available spectrometers and spectrophotometers having such
performance may be used.
[0087] In response to the command from the control means 56, the
marking means 54 marks a region where the plasma state did not
satisfy one of formulas a to c for 1 second or more. Marking will
be described later in further detail.
[0088] The marking method using the marking means 54 is not
particularly limited and marking methods capable of detection after
the gas barrier layer has been formed are all available.
[0089] For example, in cases where the gas barrier film (product
using the inventive production method) is transparent, it is
preferred to put visible marks as by laser marking with laser beams
or by coloring using various recording heads.
[0090] The mark may be one capable of detection with infrared light
or ultraviolet light. Alternatively, marking may be made by
perforation with laser beams or mechanical means.
[0091] The marking position is also not particularly limited but is
preferably outside the region for use as the product in the
substrate having the gas barrier layer formed thereon. For example,
the elongated substrate Z as in the illustrated embodiment is
preferably marked in the vicinity of an end in its width direction
perpendicular to the longitudinal direction.
[0092] Marking may be made on the gas barrier layer or the back
surface of the substrate Z on which no gas barrier layer was
deposited. The gas barrier layer may be cracked due to the marking
depending on the strength of the gas barrier layer and the
magnitude of impact from the marking. Therefore, in view of this
point, it is more advantageous to mark the back surface of the
substrate Z.
[0093] In addition, marking may be continuously made over the whole
region where the plasma state does not satisfy formulas a to c.
Alternatively, marking may be made at the forward end and the rear
end of the region where the plasma state does not satisfy formulas
a to c so that the forward end and the rear end may be
identified.
[0094] Upon receipt of the measurement results of the emission
intensities A to D from the plasma emission measurement means 52,
the control means 56 controls the amount of at least one material
supplied from the gas supply means 46, the plasma excitation power
supplied from the RF power source 48, and the amount of air
discharged from the film deposition chamber 14 by the vacuum
evacuation means 50 such that the plasma for depositing the gas
barrier layer by plasma-enhanced CVD using the foregoing materials
has the emission intensities A to D satisfying the following three
formulas:
2<B/A<20 Formula a
C/B<2 Formula b
0.5<D/B<50. Formula c
Instead of or in addition to the above factors, the control means
56 may control the substrate bias power so as to satisfy the three
formulas in cases where the drum 36 is used to apply AC or DC bias
power to the substrate Z.
[0095] In various film deposition techniques by means of
plasma-enhanced CVD, it is known to measure the emission derived
from radicals existing in the film deposition system and to control
the film deposition in accordance with the measured emission
intensities.
[0096] The inventor of the present invention has made intensive
studies on the control of the film deposition using emission
derived from radicals existing in the film deposition system in
order to obtain a gas barrier layer having excellent gas barrier
properties, oxidation resistance in a high temperature and high
humidity environment and transparency (optical transparency in a
visible light region) in the production of the gas barrier layer by
means of plasma-enhanced CVD using the material having at least one
Si--H bond such as silane, the material having at least one N--H
bond such as ammonia and at least one of nitrogen gas, hydrogen gas
and a noble gas.
[0097] As a result, it has been found that the ratios between the
emission intensity A of emission at 414 nm of those derived from
SiH radicals, the emission intensity B of emission at 336 nm of
those derived from NH radicals, the emission intensity C of
emission at 337 nm of those derived from N.sub.2 radicals, and the
emission intensity D of emission at 656 nm of those derived from H
radicals are suitable indicators of the gas barrier properties,
oxidation resistance and transparency of the gas barrier layer.
[0098] In addition, it has also been found that the gas barrier
layer having excellent gas barrier properties, oxidation resistance
and transparency is obtained by the film deposition using such a
plasma that the ratios B/A, C/B and D/B of the emission intensities
at the respective wavelengths derived from the radicals may fall
within proper ranges.
[0099] As described above, formula a is represented by
2<B/A<20.
[0100] More specifically, formula a shows the relationship between
the emission intensity A at 414 nm derived from SiH radicals and
the emission intensity B at 336 nm derived from NH radicals.
[0101] In the deposition of the gas barrier layer by means of
plasma-enhanced CVD using the above-described materials, a too
small amount of the nitrogen source with respect to the silicon
source tends to lower the transparency, whereas a too large amount
of the nitrogen source tends to lower the oxidation resistance.
Therefore, the plasma having a ratio B/A of 2 or less cannot ensure
sufficient transparency. On the other hand, the plasma having a
ratio B/A of 20 or more cannot achieve sufficient oxidation
resistance.
[0102] B/A is preferably in the range of 3<B/A<12. More
preferred results can be obtained at a ratio B/A within the
above-defined range because more excellent transparency and
oxidation resistance can be ensured, more excellent gas barrier
properties can be obtained, and the material costs can be
reduced.
[0103] Formula b is represented by C/B<2.
[0104] More specifically, formula b shows the relationship between
the emission intensity C at 337 nm derived from N.sub.2 radicals
and the emission intensity B at 336 nm derived from NH
radicals.
[0105] In the deposition of the gas barrier layer by means of
plasma-enhanced CVD using the above-described materials, a too
large amount of nitrogen source tends to lower the oxidation
resistance of the gas barrier layer and particularly N.sub.2 gas
tends to more adversely affect the oxidation resistance than
NH.sub.3 gas. This is presumably because N.sub.2 radicals formed
from N.sub.2 gas more adversely affect the oxidation resistance
than NH radicals formed from NH.sub.3 containing gas such as
NH.sub.3 gas. Therefore, the plasma having a ratio C/B of 2 or more
cannot achieve sufficient oxidation resistance.
[0106] C/B is preferably in the range of 0.1<C/B<1.7. More
preferred results can be obtained at a ratio C/B within the
above-defined range because higher oxidation resistance can be
obtained and the material costs can be reduced.
[0107] Formula c is represented by 0.5<D/B<50.
[0108] More specifically, formula c shows the relationship between
the emission intensity D at 656 nm derived from H radicals and the
emission intensity B at 336 nm derived from NH radicals.
[0109] In other words, formula c is indicative of the degree of
degradation of the material having at least one N--H bond and the
degree of degradation of the material having at least one Si--H
bond. At a plasma having a ratio D/B of 0.5 or less, the
degradation of the material having at least one N--H bond is too
small, making it impossible to obtain sufficient gas barrier
properties and oxidation resistance. On the other hand, in the
plasma having a ratio D/B of at least 50, a too large amount of H
radicals is present within the film deposition system to cause
inconveniences such as deterioration of the flexibility of the gas
barrier film and reduction of the film deposition rate, that is,
productivity. The transparency is also reduced because of a small
amount of nitrogen source.
[0110] D/B is preferably in the range of 1<D/B<20. More
preferred results can be obtained at a ratio D/B within this range
because more excellent gas barrier properties and oxidation
resistance can be obtained, sufficient flexibility is obtained,
sufficient transparency is obtained, excellent gas barrier
properties and oxidation resistance can be consistently obtained
under varying film deposition conditions and varying emission
intensities, and the material costs can be reduced (the film
deposition rate can be improved).
[0111] In addition, a combination of formula a with formula c also
enables the preferred range of D/A to be defined to obtain a
preferred degree of degradation in the material having at least one
Si--H bond.
[0112] As described above, the gas barrier layer produced by the
production method of the present invention has not only excellent
gas barrier properties but also excellent oxidation resistance and
transparency.
[0113] For example, the gas barrier film for use in solar batteries
is required to be able to have a moisture vapor transmission rate
of not more than 3.times.10.sup.-3 [g/(m.sup.2day)] and to retain
the gas barrier properties even in an environment of 85.degree. C.
and 85% RH (e.g., even after having been allowed to stand for 1000
hours). The gas barrier film for use in various displays such as
organic EL displays is required to be able to have a higher
moisture vapor transmission rate of not more than 1.times.10.sup.-5
[g/(m.sup.2day)] and to retain the gas barrier properties even in
an environment of 60.degree. C. and 90% RH (e.g., even after having
been allowed to stand for 1000 hours).
[0114] The production method of the present invention is capable of
consistently producing the gas barrier films satisfying both the
requirements. According to the present invention, the gas barrier
layer has excellent oxidation resistance and therefore there is no
need to separately deposit an inorganic film for ensuring the
oxidation resistance. In addition, the production method of the
present invention can form the gas barrier layer that has excellent
gas barrier properties even in the monolayer structure.
Accordingly, the present invention can minimize the reduction of
the transparency due to the deposition of another layer and also
the reduction of the productivity due to an increase in the number
of layers.
[0115] The side of the gas barrier layer contacting the substrate
may be oxidized when an organic material having low gas barrier
properties such as a PET film, a polyacrylate film or a
polymethacrylate film is used for the substrate Z or the base
material of the substrate Z during the production of the gas
barrier film having the gas barrier layer deposited on the
elongated substrate Z as in the illustrated production device
10.
[0116] In other words, in cases where a gas barrier film is
produced by depositing the gas barrier layer on the substrate Z
having low gas barrier properties and the produced gas barrier film
is exposed to an easily-oxidizable environment during storage in a
warehouse or during the transport, moisture in the environment
permeate the substrate Z to reach and oxidize the gas barrier
layer. As a result, the gas barrier layer is oxidized not only on
the surface side contacting air but also at the interface with the
substrate Z. In this way, the gas barrier layer is oxidized on both
sides of the surface contacting air and the surface contacting the
substrate Z to deteriorate the gas barrier properties.
[0117] In contrast, the gas barrier layer produced by the
production method of the present invention has highly excellent
oxidation resistance and can therefore prevent not only the
oxidation of the surface contacting air but also the oxidation of
the surface contacting the substrate Z due to moisture that has
permeated the substrate Z to reach the gas barrier layer.
[0118] In other words, the gas barrier layer production method of
the present invention can be used with particular advantage for
producing or depositing the gas barrier layer on the substrate or
base material comprising an organic material having low gas barrier
properties such as a PET film, a PEN film, a polyacrylate film or a
polymethacrylate film.
[0119] As described above, the gas barrier layer produced according
to the present invention also has excellent transparency.
[0120] The present invention can consistently produce a gas barrier
layer having an average visible light transmittance at 400 to 700
nm of at least 88%. Therefore, the present invention can be more
advantageously used for the applications requiring the transparency
such as production of a gas barrier film for various displays and a
gas barrier film for solar batteries.
[0121] In cases where a PET film having a transmittance of 89% is
used for the substrate, the gas barrier layer itself is required to
have a transmittance of at least 98% in order to achieve a gas
barrier film transmittance of at least 88%. Although it is very
difficult to ensure the transparency in the gas barrier layer which
contains a large amount of silicon and has excellent oxidation
resistance, the production method of the present invention is
capable of easily producing such a gas barrier layer in a
consistent manner.
[0122] There is no particular limitation on the film deposition
conditions in the gas barrier layer production method of the
present invention except that the gas barrier layer is formed by
using the plasma which has the emission intensities A to D
satisfying formulas a to c.
[0123] Therefore, as in the formation of a silicon nitride film for
the gas barrier layer by a conventional plasma-enhanced CVD
technique, the conditions of film deposition such as the flow rates
of the materials, the film deposition pressure, the plasma
excitation power, and the frequency of the plasma excitation power
may be appropriately set in accordance with the film deposition
rate to be applied, the thickness of the gas barrier layer to be
obtained, the types of the materials used, the layout and size of
the film deposition chamber, and the physical properties of the
substrate Z or the base material of the substrate Z such that the
above formulas may be satisfied.
[0124] The thickness of the gas barrier layer is also not
particularly limited and may be appropriately set in accordance
with the application and the required gas barrier properties so
that sufficient gas barrier properties may be exhibited. However,
the gas barrier layer preferably has a thickness of at least 5 nm
because the gas barrier layer surface may be almost naturally
oxidized at a gas barrier layer thickness of less than 5 nm.
[0125] A film having low oxidation resistance is easily formed at a
film deposition rate of more than 300 nm/min with the substrate Z
at rest (in terms of static film deposition rate). Therefore, the
effect of the present invention that the gas barrier layer formed
has excellent gas barrier properties and oxidation resistance can
be more advantageously achieved by depositing the gas barrier layer
at the above-defined film deposition rate.
[0126] The control means 56 and the marking means 54 as well as the
method of producing the gas barrier layer according to the present
invention are described below in further detail by referring to the
operations for forming the gas barrier layer in the film deposition
chamber 14.
[0127] As described above, upon mounting of the substrate roll 20
on the rotary shaft 24, the substrate Z is let out from the
substrate roll 20 and travels along the predetermined travel path
along which the substrate Z in the feed chamber 12 is guided by the
guide roller 26 to reach the film deposition chamber 14, where the
substrate Z is guided by the guide roller 40, wrapped over a
predetermined region of the peripheral surface of the drum 36 and
guided by the guide roller 42 to reach the take-up chamber 16,
where the substrate Z is guided by a guide roller 58 to reach the
take-up shaft 30.
[0128] The substrate Z fed from the feed chamber 12 and guided by
the guide roller 40 along the predetermined path travels on the
predetermined travel path as it is supported/guided by the drum 36.
The internal pressure of the film deposition chamber 14 is reduced
by the vacuum evacuation means 50 to a predetermined degree of
vacuum. The internal pressures of the feed chamber 12 and the
take-up chamber 16 are reduced by the vacuum evacuation means 28
and 60 to predetermined degrees of vacuum, respectively.
[0129] In addition, the gas supply means 46 supplies to the shower
head electrode 38 materials, more specifically the material having
at least one Si--H bond, the material having at least one N--H
bond, and at least one of nitrogen gas, hydrogen gas and a noble
gas. In this way, the materials are supplied from the shower head
electrode 38 to the space between the shower head electrode 38 and
the substrate Z or the drum 36.
[0130] Upon stabilization of the amounts of supplied materials and
the degree of vacuum in the film deposition chamber 14, the RF
power source 48 supplies the plasma excitation power to the shower
head electrode 38.
[0131] In the illustrated production device 10, the drum 36 serves
as a counter electrode and forms with the shower head electrode 38
an electrode pair in CCP-CVD, as described above.
[0132] The plasma excitation power is supplied to the shower head
electrode 38 to cause plasma excitation in the space between the
shower head electrode 38 and the drum 36 to generate radicals from
the materials, whereby the gas barrier layer is formed by CCP-CVD
on the surface of the substrate Z which is traveling as it is
supported by the drum 36.
[0133] In the film deposition chamber 14, the plasma emission
measurement means 52 measures the emission intensity A at 414 nm,
the emission intensity B at 336 nm, the emission intensity C at 337
nm and the emission intensity D at 656 nm during the deposition of
the gas barrier layer and sends the measurements to the control
means 56.
[0134] Upon receipt of the measurement results on the plasma
emission intensity, the control means 56 calculates B/A, C/B and
D/B and determines whether the calculated values fall within the
specified ranges defined by formulas a to c.
[0135] In cases where the emission intensities A to D do not
satisfy at least one of formulas a to c, the control means 56
adjusts at least one of the plasma excitation power supplied from
the RF power source 48 to the shower head electrode 38, the flow
rate of at least one material supplied from the gas supply means 46
to the shower head electrode 38, and the amount of air discharged
by the vacuum evacuation means 50 so that the plasma may have the
emission intensities A to D satisfying all of formulas a to c.
[0136] More specifically, the control means 56 measures the
emission intensity A of emission at 414 nm derived from SiH
radicals, emission intensity B of emission at 336 nm derived from
NH radicals, the emission intensity C of emission at 337 nm derived
from N.sub.2 radicals, and the emission intensity D of emission at
656 nm derived from H radicals, and feedback-controls at least one
of the plasma excitation power, the amount of at least one material
supplied and film deposition pressure based on the measurement
results of the emission intensity from the plasma emission
measurement means 52 such that the plasma may have the emission
intensities A to D satisfying all of formulas a to c. In cases
where the bias power is applied to the substrate, the control means
56 may feedback-control the substrate bias power so that the plasma
may have the emission intensities A to D satisfying all of formulas
a to c. The feedback control of the substrate bias power may be
carried out instead of or in addition to the control of the plasma
excitation power.
[0137] As described above, the present invention is capable of
consistently producing the gas barrier layer having excellent gas
barrier properties, oxidation resistance and transparency over a
long period of time not under the control based on the device
parameters but under the control in accordance with the plasma
state during film deposition.
[0138] In actually measuring the emission intensities at the
wavelengths derived from the radicals, the wavelength offset
(initial displacement) may often be different depending on the
plasma emission measurement means 52 (spectrometer). In such a
case, modification of the wavelength at which measurement is made,
adjustment of the measurement means and correction may be
appropriately performed in accordance with the characteristics
(e.g., wavelength offset) of the plasma emission measurement means
52 used such that the emission intensities at the wavelengths
derived from SiH radicals, NH radicals, N.sub.2 radicals and H
radicals may be measured, respectively.
[0139] The wavelength of the emission intensity B (336 nm) is close
to that of the emission intensity C (337 nm) and both the
intensities may overlap each other. However, peak separation using
information processing is not necessary if the emission intensities
at both the wavelengths can be measured separately.
[0140] In cases where the emission intensities A to D do not
satisfy at least one of formulas a to c for at least 1 consecutive
second (this state is hereinafter also referred to as "improper
state"), the control means 56 issues a command to the marking means
54 to cause the marking means 54 to mark the region where the gas
barrier layer was formed in this improper state (this region is
hereinafter also referred to as "improper region"). For example in
cases where the improper state continued for 1 second or more, the
control means 56 detects the whole region of the substrate Z that
faced the shower head electrode 38 from the beginning of the
improper state to the restoration of the proper state after the end
of the improper state and issues a command to the marking means 54
to cause the marking means 54 to mark the detected whole region as
the improper region.
[0141] In response to the command, the marking means 54 marks the
surface of the gas barrier layer by, for example, laser marking
with laser beams.
[0142] The improper region where the gas barrier layer was formed
with the improper state continued for 1 second or more has no
desired performance and is preferably removed.
[0143] Therefore, such a marking operation facilitates the
detection of any improper region after the gas barrier layer has
been formed.
[0144] In the meantime, the substrate used in the production method
of the present invention may be one having many layers (films)
formed on the base material B as shown in FIG. 2. In order to
minimize the reduction of the gas barrier properties due to pin
holes, a plurality of gas barrier layers may often be formed with
different layers interposed therebetween.
[0145] For example, the embodiment shown in FIG. 2 may be such that
layers b, d and f are the gas barrier layers and layers a, c and e
are layers having other functions.
[0146] The travel speed of the substrate Z is of course well known.
Therefore, it is possible to detect the improper region under time
control. However, in cases where the multi-layered gas barrier film
is formed as described above, mounting of the substrate roll 20 on
the rotary shaft 24 and traveling of the substrate to the take-up
shaft 30 may very often cause errors in the position of the
improper region under time control.
[0147] In this regard, marking which is capable of visual detection
(i.e., detection with visible light) such as marking with laser
beams or which is capable of detection with, for example, infrared
light ensures the detection of the improper region even in cases
where such multi-layered gas barrier film is formed.
[0148] Therefore, even in cases where such multi-layered gas
barrier film is formed, the marking operation ensures that the
improper region in each layer of the multi-layered gas barrier film
is detected to prevent improper products from being provided.
[0149] The substrate Z having the gas barrier layer formed thereon
(i.e., gas barrier film) travels from the drum 36 to the guide
roller 42 and is guided by the guide roller 42 to pass through a
slit 57a formed in a partition wall 57 separating the film
deposition chamber 14 from the take-up chamber 16, thus reaching
the take-up chamber 16.
[0150] In the illustrated embodiment, the take-up chamber 16
includes the guide roller 58, the take-up shaft 30 and the vacuum
evacuation means 60.
[0151] The substrate Z (gas barrier film) having reached the
take-up chamber 16 travels to the take-up shaft 30 as it is guided
by the guide roller 58 and is wound on the take-up shaft 30 to form
a roll, which is then supplied to the subsequent step as a roll of
gas barrier film.
[0152] The take-up chamber 16 is also provided with the vacuum
evacuation means 60 as in the above-described feed chamber 12 and
during film deposition, its pressure is reduced to a degree of
vacuum suitable for the film deposition pressure in the film
deposition chamber 14.
[0153] In the film deposition chamber 14 of the illustrated
production device 10, the control means 56 is of a configuration
capable of feedback control of the plasma excitation power from the
RF power source 48, the amount of at least one material supplied
from the gas supply means 46, and the amount of air discharged by
the vacuum evacuation means 50 based on the measurement results of
the emission intensities A to D from the plasma emission
measurement means 52.
[0154] However, this is not the sole case of the present invention,
and only one of the plasma excitation power, amount of at least one
material supplied and the degree of vacuum (pressure) may be
controlled (with a controllable unit). Alternatively, at least two
of the plasma excitation power, amount of at least one material
supplied and the degree of vacuum may be controlled (with a
controllable unit). The substrate bias power may be controlled
alone or in combination with the excitation power or the like.
[0155] At least the plasma excitation power is preferably
controlled to use the plasma that has the emission intensities A to
D satisfying formulas a to c to thereby form the gas barrier
layer.
[0156] While the method of producing a gas barrier layer according
to the present invention has been described above in detail, the
present invention is by no means limited to the foregoing
embodiments and it should be understood that various improvements
and modifications may of course be made without departing from the
scope and spirit of the invention.
[0157] For example, the production device 10 shown in FIG. 1 is a
device for producing the gas barrier layer by a roll-to-roll
system. However, the present invention is not limited to this but
may be used in a so-called batch type production device.
EXAMPLES
[0158] A common CVD device for depositing a film by CCP-CVD was
used to form a gas barrier layer on a substrate.
[0159] The substrate used was a PET film (Lumirror T60 available
from Toray Industries, Inc.; total light transmittance: 89%) with a
thickness of 100 .mu.m. The substrate had an area of 300
cm.sup.2.
[0160] A gas material including silane gas (SiH.sub.4), ammonia gas
(NH.sub.3), nitrogen gas (N.sub.2) and hydrogen gas (H.sub.2) was
used.
[0161] The power source used was an RF power source at a frequency
of 13.56 MHz.
[0162] The substrate was set on a substrate holder in a vacuum
chamber of the CVD device and the vacuum chamber was closed. Then,
the vacuum chamber was evacuated and the gas material was
introduced into the vacuum chamber at the point in time when the
pressure dropped to 0.01 Pa.
[0163] Once the pressure in the vacuum chamber had stabilized, the
plasma excitation power was supplied from the RF power source to
the electrode to deposit a gas barrier layer on the substrate
surface to prepare a gas barrier film having the PET film as the
substrate. The gas barrier layer was deposited to a thickness of 50
nm. The film thickness was controlled based on previously conducted
experiments. During film deposition, the temperature adjusting
means built into the substrate holder was used to adjust the
temperature of the substrate to 80.degree. C. or less.
[0164] During the deposition of the gas barrier layer, a plasma
emission monitor (spectrometer HR4000 available from Ocean Optics,
Inc.) was used to measure the emission intensity A of emission at
414 nm (mainly derived from SiH radicals), the emission intensity B
of emission at 336 nm (mainly derived from NH radicals), the
emission intensity C of emission at 337 nm (mainly derived from
N.sub.2 radicals), and the emission intensity D of emission at 656
nm (mainly derived from H radicals).
[0165] The film deposition pressure was changed in the range of 20
Pa to 250 Pa by adjustment with the amount of discharged air and
the gas flow rates, and the plasma excitation power was changed in
the range of 200 W to 1000 W to appropriately modify the emission
intensities A to D, whereby in total 10 types of gas barrier films
were prepared in Examples 1 to 4 and Comparative Examples 1 to
6.
[0166] In Examples 3 and 4, and Comparative Example 6, the film
deposition pressure and the total gas flow rate (sum of the flow
rates of the introduced gases) were the same. The sum of the flow
rates of the gases refers to the maximum flow rate at which the
vacuum evacuation means can maintain the film deposition pressure
in the CVD device used.
[0167] The ratios B/A, C/B, and D/B of the emission intensities in
each gas barrier film are shown in Tables 1 and 2. Examples 1 and
2, and Comparative Examples 1 to 5 are shown in Table 1, whereas
Examples 3 and 4 and Comparative Example 6 are shown in Table 2.
Table 2 also shows the film deposition rate (static film deposition
rate) (nm/min) in Examples 3 and 4, and Comparative Example 6.
[0168] Each of the prepared gas barrier films was subjected to the
measurement of moisture vapor transmission rate, oxidation
resistance and total light transmittance. The flexibility was also
measured in Examples 3 and 4, and Comparative Example 6.
[0169] Moisture Vapor Transmission Rate
[0170] The moisture vapor transmission rate [g/(m.sup.2day)] was
measured by the MOCON method. Those samples which exceeded the
limit for measurement of the moisture vapor transmission rate by
the MOCON method were measured for the moisture vapor transmission
rate by the calcium corrosion method (see JP 2005-283561 A).
Oxidation Resistance
[0171] The gas barrier film was subjected to a storage test in an
environment of 85.degree. C. and 85% RH for 1000 hours. The
composition of the film before and after the storage was determined
by X-ray photoelectron spectroscopy (abbreviated as XPS; Quantera
SXM available from Ulvac-Phi, Incorporated) to evaluate the
oxidation resistance of the film. The surface and interface
portions that were already oxidized before the storage were removed
from the whole film and the remaining region with a film thickness
of 5 to 45 nm was rated for the ratio of oxygen to nitrogen (0/N
value) based on the following criteria:
[0172] Good: The difference between before and after the storage is
within .+-.3% (substantially no change);
[0173] Fair: The ratio increase from before to after the storage is
less than 10%;
[0174] Poor: The ratio increase from before to after the storage is
10% or more.
Total Light Transmittance
[0175] A spectrophotometer (U-4100 available from Hitachi
High-Technologies Corporation) was used to measure the average
transmittance at a wavelength of 400 to 700 nm of the film
including the PET substrate.
[0176] Flexibility
[0177] The prepared gas barrier film was wound around a cylindrical
bar with a diameter of 10 mm to form 100 layers thereon, and
observed with an optical microscope or a scanning electron
microscope if cracking occurred.
[0178] A gas barrier film in which no cracking could be confirmed
was rated as "good".
[0179] A gas barrier film in which cracking could be confirmed was
rated as "poor".
[0180] Comprehensive Evaluation
[0181] The evaluation criteria used include a moisture vapor
transmission rate of not more than 3.times.10.sup.-3
[g/(m.sup.2day)], good oxidation resistance and transparency of at
least 88%.
[0182] The gas barrier film was rated as "good" when the three
evaluation criteria were met.
[0183] The gas barrier film was rated as "fair" when the moisture
vapor transmission rate and one of the remaining evaluation
criteria were met.
[0184] The gas barrier film was rated as "poor" when the evaluation
criterion of the moisture vapor transmission rate was not met.
[0185] The results are shown in Tables 1 and 2.
TABLE-US-00001 TABLE 1 Gas barrier Emission intensity properties
Oxidation Transmittance Comprehensive B/A C/B D/B [g/(m.sup.2 day)]
resistance [%] evaluation EX1 5.19 0.49 3.67 less than Good 88.4
Good 0.001 EX2 10.51 1.62 1.08 less than Good 88.4 Good 0.001 CE1
1.86 0.5 9.15 0.0017 Good 81.3 Fair CE2 23.55 1.56 0.72 0.0027 Fair
88.5 Fair CE3 17.29 2.41 0.81 0.0022 Fair 88.4 Fair CE4 12.37 1.22
0.33 0.0087 Poor 88.1 Poor CE5 20.2 1.62 0.28 0.0104 Poor 88.3 Poor
Emission intensity A: emission at 414 nm mainly derived from Si--H
Emission intensity B: emission at 336 nm mainly derived from N--H
Emission intensity C: emission at 337 nm mainly derived from
N.sub.2 Emission intensity D: emission at 656 nm mainly derived
from H
TABLE-US-00002 TABLE 2 Film Gas barrier deposition Emission
intensity properties Oxidation Transmittance rate Comprehensive B/A
C/B D/B [g/(m.sup.2 day)] resistance [%] Flexibility [nm/min]
evaluation EX3 3.57 0.41 6.33 less than Good 88.6 Good 613 Good
0.001 EX4 4.71 0.38 22.64 0.0014 Good 88.5 Good 372 Good CE6 1.06
0.71 51.67 0.29 Good 66.2 Poor 54 Poor Emission intensity A:
emission at 414 nm mainly derived from Si--H Emission intensity B:
emission at 336 nm mainly derived from N--H Emission intensity C:
emission at 337 nm mainly derived from N.sub.2 Emission intensity
D: emission at 656 nm mainly derived from H
[0186] As is clear from Tables 1 and 2, the gas barrier layer
formed by the inventive production method in which film deposition
was made with a plasma that had the emission intensities A to D all
satisfying formulas a to c is excellent in all of the gas barrier
properties, oxidation resistance in a high temperature and high
humidity environment, and transparency. As shown in Examples 3 and
4, the gas barrier layer formed by the production method of the
present invention also has excellent flexibility. Since D/B exceeds
the preferred range of less than 20, Example 4 is inferior in the
film deposition rate to Example 3 but both of the gas barrier
layers formed in Examples 3 and 4 have excellent gas barrier
properties, oxidation resistance in a high temperature and high
humidity environment, and transparency at a film deposition rate in
excess of 300 nm/min.
[0187] In contrast, Comparative Example 1 having B/A of not more
than 2 cannot achieve a sufficient transmittance and Comparative
Example 2 having B/A of at least 20 also cannot achieve sufficient
oxidation resistance. Comparative Example 3 having C/B of at least
2 cannot achieve sufficient oxidation resistance. Comparative
Example 4 having D/B of not more than 0.5 and Comparative Example 5
having B/A of at least 20 and D/B of not more than 0.5 do not have
sufficient gas barrier properties and oxidation resistance. In
addition, Comparative Example 6 having D/B in excess of 50 is
inferior in the gas barrier properties and the transmittance and
has a low film deposition rate and is therefore disadvantageous in
terms of productivity.
[0188] The above results clearly show the beneficial effects of the
present invention.
[0189] The present invention can be advantageously used in
producing various products which are required to include a gas
barrier layer having not only high gas barrier properties but also
excellent transparency and oxidation resistance, as exemplified by
various displays such as liquid crystal displays and solar
batteries.
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